GIA Diamond Cut Grading: Problems with Diamond Dock

[adamasgem]

Date: 3/20/2006 12:49:50 AM
Author: strmrdr
They told Michael they were down grading them when they arent as shown by the cert I posted earlier.

Strmdr: There is sometimes things lost or twisted in the translation from what "they" said and what is posted here, based on my personal experiance with certain people.. More later on this.. as I am considering preparing what has been termed before on a wholesale web site, "a shotgun enema" for special delivery.

An arbitrary statement about downgrading is just wrong, but it serves some people''s purpose

The amount painting has to considered in terms of the rest of the crown and pavillion parameters, based on ray trace studies, and it is the net result that AGS is analysing for performance.

AGS gave cutters examples of painting combination as a function of crown and pavilion angles versus table size that would result (for a purely symmetric stone) in a potential AGS 0 grade. These potential sets will vary with lower girdle length also.

 

[dhog]

Date: 3/20/2006 3:09:51 AM
Author: Rhino
I''ll have this out to ya Tuesday morning when I get up to the lab.

rhino:when did you recieve your dd and how long
does the light last before loosing high intensity

also from the beautiful photos of those
last arrows photos it looks to me like
you use a cannon eos 10d camera.

a photo to me shows it all with all
the details.

I had the same camera stolen and now use a
8700 nikon coolpix 8 megapixel

 

[Rhino]

Hey bossman,

Just some commentary and questions. Mine will be in bold.

Fact: Gia has a wide ranging EX group that includes diamonds I wouldn't buy.

I hear ya. The question that comes to mind, is what indeed *is* the consumer getting who does or would happen to get a stone that falls on the outskirts? It is a dog? I would not want to make rash judgements at this point in time until I've garnered consumer input.

Fact: some GIA EX diamonds are going to have have less spread than I consider optimal.

And AGS doesn't?

Fact: I dont have the answer to where in the real world I can go to make my diamond look just like it does in the D.D. with the diamond mounted and on my finger. If there isnt one then the lighting is total B.S.

Amen to this.

Fact: AGS gives ags0 to a few diamonds I wouldn't buy

Fact: AGS appears to be saying one thing but doing another with painted girdles and cut grading. Which isn't the first time for them doing that.

While Mike has made some commentary regarding information he has heard, I would note that no final word has been given just yet. There are studies by AGS that are still incomplete. I say we wait and see and let them give the final verdict.

Fact: Some consumers in direct comparisons outside of the vendors site have picked painted girdle diamonds over similar non-painted ones.
Some have picked the other way.

Absolutely. Having direct access to varying degrees of painted stones, it is easy for me to garner consumer input to collect these ratios. Our store is generally always busy plus I have direct access to plenty of ambient and diffuse daylight as the windows in front of our store are huge.

Fact: I don't like the looks of the painted girdle diamonds Iv seen including 8*.

Understood.

Fact: the average diamond sold in the US everyday is what Id consider a crap cut.

Sad but true.

Fact: Im losing a lot of respect for a lot of people over the way they have been acting in these threads.

If that includes me, my apologies.

Fact: No one has bothered answered my orginal questions on the first page of this thread:

couple questions:
1> diamonds are often viewed at angles like that on the hand. How is that different?

From the original charts posted it doesn't seem different at all actually. Diamonds will generally be tilted towards the face of the observer (like the angle depicted in the charts Leo posted) and light coming from above and/or behind and in front of the head of the viewer. Each lighting environment can vary as the strength of the light sources can change as the observer moves or changes position. Also note there is body obstruction as well as head obstruction. This however does not mean that face up appearance can not be judged as there are common optical properties certain diamonds will share or "appear in" in most viewing circumstances depicting a similar optical characteristic.

For example when viewing the optical metric/characteristic of brightness, there are certain elements that will change while certain others remain the same. Ie. the brighter the lighting or brighter the walls in that area, the stronger the reflections of white light will be within the diamond. In dimmer circumstances the reflections will be not as intense. However, if a diamond is painted to the point where it impacts face up appearance you will be able to observe that phenomena in many environments that depict brightness. I will demonstrate this with some photography.

2> the human head is always moving so wouldnt they pick up the other beams graphed there?

Absolutely strm.

Fact: im rather annoyed right now
...............

I can tell.

Sorry for not addressing your questions on the first page earlier.

This first photo was taken outside in daylight but in the shade. It doesn't get more natural than this. Can you identify the stone with the painted girdle?

NOTE: These graphics had writing in them which I cloned out for this which is why you see an edit on my thumb.

 

[Rhino]

This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn't account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

 

[Rhino]

Here is yet another in standard office lighting, obviously not as bright as the other 2 conditions.

Can you identify which is which? This is perhaps the more challenging photo in my opinion.

 

[Rhino]

Date: 3/20/2006 3:43:01 AM
Author: dhog


rhino:when did you recieve your dd and how long
does the light last before loosing high intensity

Late Dec early Jan. Can''t remember precisely.


How long ... good question. I''ll have to foward that.

Date: 3/20/2006 3:43:01 AM
Author: dhog

also from the beautiful photos of those
last arrows photos it looks to me like
you use a cannon eos 10d camera.

a photo to me shows it all with all
the details.

I am a Canon man. Good call.

We have a 10d and a 20d here which we use for our photography.


The Nikon''s are also excellent camera''s. I had the 5700 5 megapixel and besides eating batteries fast, it was an excellent cam. I understand the later model like you have doesn''t suck up the batteries so quickly now.

Peace,
Jon

 

[Serg]

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn''t account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Rhino,
I think left diamond have bigger camera and body obscuration( Lens axis had been moved to left)
If you want receive correct photos from close up position , You should
1) Fix photocamera, use manual fix mode ( for focus, aperture and exposure) go far from camera( We do photos from computer remote control)
2) Do shot
3) to Change position of diamonds( but not move anything other. Holder should be fix too)
4) Publish 2 photos with better quality.

 

[Serg]

Date: 3/20/2006 4:37:15 AM
Author: Serg

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn't account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Rhino,
I think left diamond have bigger camera and body obscuration( Lens axis had been moved to left)


If you want receive correct photos from close up position , You should
1) Fix photocamera, use manual fix mode ( for focus, aperture and exposure) go far from camera( We do photos from computer remote control)
2) Do shot
3) to Change position of diamonds( but not move anything other. Holder should be fix too)
4) Publish 2 photos with better quality.

BTW.
Rhino,

What lens do you use ? ( for such photos I prefer 100 mm Macro)
What is photo distance?

 

[Garry H (Cut Nut)]

Date: 3/20/2006 2:30:47 AM
Author: Rhino

Date: 3/20/2006 12:26:02 AM
Author: Garry H (Cut Nut)

Have you just got back from a sales training conference Rhino?

LOL! NO!

Date: 3/20/2006 12:26:02 AM
Author: Garry H (Cut Nut)

I am not saying that the LED desk lights being sold to lots of retailers and used in DD are good - I am saying they should be destroyed on sight.

I have never agreed with anyone who says high colored temp fluoro''s have any use anywhere in the jewellery industry - for any purpose from red reflectors to color grading and especially for cut grading.

But mostly I disagree with using any light that is closer than 2 meters from a diamond for visual cut grading.

Question 1: What lighting environment do you suggest a consumer view fire in when visiting their local jewelry store? an area with 2 to 5 halogens in the ceiling at least 2 meters away
Question 2: What lighting environment do you suggest a consumer view brightness in when visiting their local jewelry store? in my store I take people to the window and have them hold the stone up so the light comes from behind them, and under a section with fluoro''s (in the ceiling) - and also under the desk well out of any direct light source - but not under a close up desk light.

Here''s another question to ponder.

If bright lighting with white backgrounds make steep deeps look good ... reverse the roles for a sec mate. What would be an equally worse mistake? light only from very low angles makes a steep deep very firey around the outside edges

What I''m getting at here is this. Think of common real world everyday engagement ring conditions. Would you say most of the consumers buying engagement rings are having their diamonds mounted in prongs or bezels?
http://www.preciousmetals.com.au/product/catalogue.asp you will find most of the styles that sell outside USA are about 1/2 the height, with far less chance of back light aiding the diamond. I suspect that around 50% of GIA graded diamonds are sold outside USA.
If prongs, now think about this ... is the pavilion covered with no light being allowed from behind?

Would you say the background is bright white (such as the white paper under a desk lamp in most diamantaires offices), inky black (like the background you use to compare the cz''s) or perhaps a more neautral color (such as metal or skin underneath the diamond)?

There is however a good time to use a black background to make a judgement however if you do want to reflect real world conditions. What type of setting completely encases the pavilion and prevents any light or color from being transmitted through the top? every pendant and stud earring, and most rings because most of the light from the floor is insufficient to light up the stone - where as the Diamond Dock tray gets direct light FROM the leakage, which then makes the underneath of the pavilion in very leaky stones brighter than they would appear in a real world setting. You Rhino have often explained to people how a set diamond with "a ring of death" will have an ugly dark zone.
Peace,

I am amazed you have read my article and still try to defend the Diamond Dock Rhino?

Surely you have tested these things for your self by now?
Take some clients repairs with steep deep stones - and look at them dirty - as they are at book in time - and then clean them and look again - you will see that any stone with a ring of death in the real world will look shocking in that dark zone. If it is in a ring - be sure to look at it or photograph it on a finger in a ''normal'' situation.

 

[Garry H (Cut Nut)]

Date: 3/20/2006 2:41:10 AM
Author: Rhino

Absolutely John. My point however was that if we''re going to level criticisms and accusations against GIA for allowing up to a 63% depth, no mention will be made of allowing 62.8? I am for honest critique, I just don''t like to see it aimed squarely at one lab when the other is just .2% away. That''s all. I have my own criticisms about both systems and were I to develop a cut grading system of my own would consist of different standards. I do realize however that my grading is not practical for the industry as a whole and I would say ... neither would Brians. We''re both too anal.

Peace,

AGS could accept stones over 63% deoth because they use a minimum spread of 95% compared to Tolkowsky.
GIA seem to be using depth % alone - this is a blunt instrument and appears to allow stones up to or just below 63% - in this case spread can be about 8% if the girdle is near the maximum allowed for slightly thick (which is quite a lot thicker than AGS''s girdle system for smaller diameter stones).


(BTW i prefer GIA''s girdle asessment system to AGS''s)

 

[Garry H (Cut Nut)]

Date: 3/20/2006 3:05:09 AM
Author: Serg
re:The bigger the better - say 3/4ct - in a perfect world the stones are all either the same diameter and different weights - but all in the same weight / price grid - or the same diameter but different weights. This is what i tried to do with my Diamond Dock study.


Garry, I prefer same diameter for all diamonds. 6mm<>3/4 ct

I think about 5.7mm then - most rough that makes 0.80 round is used for other shapes.
.80ct is rare and far more expensive than .70ct to .75ct.

 

[Garry H (Cut Nut)]

There has been a lot of discussion about how many degrees or clicks of painting is acceptable.

please please understand that painting is another variable just like minor facets - it can be good - it can be bad - it depends on the combined relationships between crown and pavilion angles and tabel size.

I posted an example of a poor stone made better with quite elaborate and complex painting

It is about 1/3rd the way down on this page- page 4 of this discussion
https://www.pricescope.com/community/threads/gia-diamond-cut-grading-problems-with-diamond-dock.41869/page-4

Don''t try to make things that are complex into something simple.

 

[Shay37]

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn''t account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Just going to take a shot in the dark here. I hope I guess right, but after studying the photo, I''m going to say painted on the left.

shay

 

[michaelgem]

/idealbb/editor/cute/images/emlove.gif

I heart super-ideals with painted or normally indexed top halves

Many appear to be reading in to my posts on the commonalities between AGS and GIA that I have a problem with painting.

I do not, and nothing could be further from the truth. In fact I have expressed my confusion to both organizations as to why they both recommend against painting.

Like John and Brian, who sell optically symmetric, super-ideals with both painted and regularly indexed top halves, I find these diamonds superior in beauty to the average AGS0 or GIA Excellent.

I tell my clients that while AGS sets their “bar for beauty” higher than does GIA, my diamonds “answer to a higher authority” . I sell super-ideal cuts with high optical symmetry and proportions that yield the best in the attributes of diamond beauty, brilliance (both brightness and contrast), fire and scintillation.

From what I have seen, the painted diamonds offered by companies like Brian’s and the normally indexed, optically-symmetric super-ideals like those cut by Paul Slegers both satisfy my super-ideal cut criteria.

Michael Cowing

www.acagemlab.com

 

[Serg]

Date: 3/20/2006 9:20:20 AM
Author: michaelgem

I heart super-ideals with painted or normally indexed top halves

Many appear to be reading in to my posts on the commonalities between AGS and GIA that I have a problem with painting.

I do not, and nothing could be further from the truth. In fact I have expressed my confusion to both organizations as to why they both recommend against painting.

Like John and Brian, who sell optically symmetric, super-ideals with both painted and regularly indexed top halves, I find these diamonds superior in beauty to the average AGS0 or GIA Excellent.

I tell my clients that while AGS sets their “bar for beauty” higher than does GIA, my diamonds “answer to a higher authority” . I sell super-ideal cuts with high optical symmetry and proportions that yield the best in the attributes of diamond beauty, brilliance (both brightness and contrast), fire and scintillation.

From what I have seen, the painted diamonds offered by companies like Brian’s and the normally indexed, optically-symmetric super-ideals like those cut by Paul Slegers both satisfy my super-ideal cut criteria.

Michael Cowing

www.acagemlab.com

Michael,

Please publish two simple answer

1) What is GIA cut grade for Brain or Paul diamonds?
2) What is AGS cut grade for Brain or Paul diamonds?

It will stop commonalities game.

 

[dhog]

Date: 3/20/2006 3:49:59 AM
Author: Rhino
Hey bossman,


Just some commentary and questions. Mine will be in bold.

Fact: Gia has a wide ranging EX group that includes diamonds I wouldn''t buy.


I hear ya. The question that comes to mind, is what indeed *is* the consumer getting who does or would happen to get a stone that falls on the outskirts? It is a dog? I would not want to make rash judgements at this point in time until I''ve garnered consumer input.



Fact: some GIA EX diamonds are going to have have less spread than I consider optimal.


And AGS doesn''t?



Fact: I dont have the answer to where in the real world I can go to make my diamond look just like it does in the D.D. with the diamond mounted and on my finger. If there isnt one then the lighting is total B.S.


Amen to this.



Fact: AGS gives ags0 to a few diamonds I wouldn''t buy


Fact: AGS appears to be saying one thing but doing another with painted girdles and cut grading. Which isn''t the first time for them doing that.


While Mike has made some commentary regarding information he has heard, I would note that no final word has been given just yet. There are studies by AGS that are still incomplete. I say we wait and see and let them give the final verdict.



Fact: Some consumers in direct comparisons outside of the vendors site have picked painted girdle diamonds over similar non-painted ones.

Some have picked the other way.


Absolutely. Having direct access to varying degrees of painted stones, it is easy for me to garner consumer input to collect these ratios. Our store is generally always busy plus I have direct access to plenty of ambient and diffuse daylight as the windows in front of our store are huge.



Fact: I don''t like the looks of the painted girdle diamonds Iv seen including 8*.


Understood.


Fact: the average diamond sold in the US everyday is what Id consider a crap cut.


Sad but true.



Fact: Im losing a lot of respect for a lot of people over the way they have been acting in these threads.


If that includes me, my apologies.



Fact: No one has bothered answered my orginal questions on the first page of this thread:


couple questions:

1> diamonds are often viewed at angles like that on the hand. How is that different?


From the original charts posted it doesn''t seem different at all actually. Diamonds will generally be tilted towards the face of the observer (like the angle depicted in the charts Leo posted) and light coming from above and/or behind and in front of the head of the viewer. Each lighting environment can vary as the strength of the light sources can change as the observer moves or changes position. Also note there is body obstruction as well as head obstruction. This however does not mean that face up appearance can not be judged as there are common optical properties certain diamonds will share or ''appear in'' in most viewing circumstances depicting a similar optical characteristic.


For example when viewing the optical metric/characteristic of brightness, there are certain elements that will change while certain others remain the same. Ie. the brighter the lighting or brighter the walls in that area, the stronger the reflections of white light will be within the diamond. In dimmer circumstances the reflections will be not as intense. However, if a diamond is painted to the point where it impacts face up appearance you will be able to observe that phenomena in many environments that depict brightness. I will demonstrate this with some photography.



2> the human head is always moving so wouldnt they pick up the other beams graphed there?


Absolutely strm.



Fact: im rather annoyed right now

...............


I can tell.

Sorry for not addressing your questions on the first page earlier.

This first photo was taken outside in daylight but in the shade. It doesn''t get more natural than this. Can you identify the stone with the painted girdle?


NOTE: These graphics had writing in them which I cloned out for this which is why you see an edit on my thumb.

the photo to me that you posted looks to be
dark in all corners. I WOULD SUGGEST looking for other
lighting enviroments and or look into the following

HDR-HC1 owners should be very careful when trying to mount a filter behind the stock lens hood. My UV filter moves the hood forward about .225" causing still images to vignette (darkening at the corners) at widest zoom. Video is fine - no vignetting. However, still images have a wider field of view and have a serious problem.

rhino do you really like using video camcorders to take
still shots.

 

[michaelgem]

Strmrdr,

I enjoyed your post. You really "throw down the gauntlet".

I would have to spend hours explaining why I agree or disagree which your individual "facts". At the risk of boring some by repetition, I want to repeat the points that got my greatest attention and comment where most important.

Date: 3/19/2006 11:52:52 PM
Author: strmrdr

I''m looking but I get tired of the ranting and agenda thrashing and do so in private.
Every once in the while I will join in on here, but its rather frustrating when the signal/noise ratio is 1s/1000000n
.....
Fact: some GIA EX diamonds are going to have less spread than I consider optimal.

Fact: AGS gives ags0 to a few diamonds I wouldn''t buy

Fact: AGS appears to be saying one thing but doing another with painted girdles and cut grading. Which isn''t the first time for them doing that.

Fact: Some consumers in direct comparisons outside of the vendors site have picked painted girdle diamonds over similar non-painted ones. Some have picked the other way.

Fact: I don''t like the looks of the painted girdle diamonds Iv seen including 8*.

Fact: the average diamond sold in the US everyday is what Id consider a crap cut.

Fact: Im losing a lot of respect for a lot of people over the way they have been acting in these threads.

Fact: No one has bothered answered my orginal questions on the first page of this thread:

couple questions:
1> diamonds are often viewed at angles like that on the hand. How is that different?

It is not too different. Whether viewers have the diamond in a tray or in a ring on their finger, they will judge its beauty by angling it face-up, toward their line-of-sight, and tilt it around from there. Individuals, depending upon their eyesight, will judge at a distance within arms length up to a close-focusing distance of about 7 to 10 inches.

2> the human head is always moving so wouldnt they pick up the other beams graphed there?

Yes

unsupported humans just dont keep their head in one position.
Also odds are that they would move for max brightness when looking at it.
From my recall of observing people looking at diamonds most would move to find the brightest look.

This is an insightfull and important observation. People do move the diamonds around to find the brightest look. That position will be when the main lighting is close, but not too close to the observer''s line of sight and his head. Under this viewing circumstance, the best cut diamonds will be preferred in brilliance (both brightness and contrast), fire and scintillation.

Fact: im rather annoyed right now

Any questions?
Other than who the heck does he think he is and who made him king

 

[JohnQuixote]

Date: 3/20/2006 2:41:10 AM
Author: Rhino

Absolutely John. My point however was that if we're going to level criticisms and accusations against GIA for allowing up to a 63% depth, no mention will be made of allowing 62.8? I am for honest critique, I just don't like to see it aimed squarely at one lab when the other is just .2% away. That's all. I have my own criticisms about both systems and were I to develop a cut grading system of my own would consist of different standards. I do realize however that my grading is not practical for the industry as a whole and I would say ... neither would Brians. We're both too anal.

No system is the grading grail (yet), nor does any system conform to those who have elite paradigms - that's why were here cussin' and discussin' AGS does has limitations that GIA does not in depth/spread allowed though. ETA: Garry addressed this more cogently a few posts back.

Date: 3/20/2006 2:47:26 AM
Author: Rhino
Hi John,

What are the lower half lengths (or depths in DC) of each of those stones? I also note a slightly shallow pavilion angle. Curious. The reason why I ask about the pavilion angles is becuase if those are shallow enough to cause an overdarkening of the mains, that would disqualify a stone from the top grade as well.

Edited to add: Wouldn't you agree that GIA including this information on reports, is better than not having it at all?

Not shallow at all. 40.83. They're GIA: E-VG proportions in DC. I took my lead from your first set of graphics and darked the mains manually to show where the differences were taking place: I think you did that in your 1:31:17 AM post...unless there is a feature in DC that does this I'm not aware of (?) I created them on the fly but I had the GIA lengths appx 77.7, 80, 82.3 (DC 79.4, 81.5, 83.7).

I definitely approve of having the info. I said in my previous post that I applaud GIA for their studies and for including them. I wish it were not rounded, as the character of diamonds within 5% can be different sometimes, but if we got everything we wanted it would be too easy I suppose.

 

[JohnQuixote]

These are important comments from the last dozen posts, all in fundamental agreement.

Date: 3/20/2006 8:24:41 AM
Author: Garry H (Cut Nut)

There has been a lot of discussion about how many degrees or clicks of painting is acceptable. please please understand that painting is another variable just like minor facets - it can be good - it can be bad - it depends on the combined relationships between crown and pavilion angles and tabel size.

Don't try to make things that are complex into something simple.

Date: 3/20/2006 9:20:20 AM
Author: michaelgem



Many appear to be reading in to my posts on the commonalities between AGS and GIA that I have a problem with painting. I do not, and nothing could be further from the truth. In fact I have expressed my confusion to both organizations as to why they both recommend against painting.

Date: 3/20/2006 3:21:16 AM
Author: adamasgem

The amount painting has to considered in terms of the rest of the crown and pavillion parameters, based on ray trace studies, and it is the net result that AGS is analysing for performance.

Date: 3/20/2006 1:34:13 AM
Author: JohnQuixote

Digging/painting is required in all brillianteering techniques – it just may not be overly harsh. What level of digging should be penalized and what level of ‘painting’ constitutes ‘painting?’ Brillianteering technique is a matter of common sense. Used correctly the craftsman can apply these techniques to cover many faults or errors and still complete a cut stone complying with the requirements of the AGS - or GIA.

It's why we MUST avoid stereotyping.

In the words of the great Ron White: "That's profiling, and profiling is wrong."

 

[Rhino]

Date: 3/20/2006 4:37:15 AM
Author: Serg

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn''t account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Rhino,
I think left diamond have bigger camera and body obscuration( Lens axis had been moved to left)

Definitely not the case Sergey. In fact my head & body obstruction accounts way more for the obstruction seen than the camera. I would like to address your other points.

Date: 3/20/2006 4:37:15 AM
Author: Serg

If you want receive correct photos from close up position , You should
1) Fix photocamera, use manual fix mode ( for focus, aperture and exposure) go far from camera( We do photos from computer remote control)
2) Do shot
3) to Change position of diamonds( but not move anything other. Holder should be fix too)
4) Publish 2 photos with better quality.

It is my conviction that if I followed these instructions I would not be true to representing the actual apperance I am seeing Sergey. I realize a still shot may be a little more dramatic since the observer can stare while there is no movement but these optical characteristics are visible none-the-less. If I set up the camera without my body behind it, then the picture would not account for proper head and body obstruction which every single viewer will see if they were to look at the diamonds live and in person.

If you prefer I can show you pictures of the 2 stones and change positions. I believe I can tell you right now what the results will be but if you like I''ll do it.

Regards,
Jonathan

 

[Rhino]

Date: 3/20/2006 4:41:59 AM
Author: Serg

Date: 3/20/2006 4:37:15 AM
Author: Serg

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn''t account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Rhino,
I think left diamond have bigger camera and body obscuration( Lens axis had been moved to left)



If you want receive correct photos from close up position , You should
1) Fix photocamera, use manual fix mode ( for focus, aperture and exposure) go far from camera( We do photos from computer remote control)
2) Do shot
3) to Change position of diamonds( but not move anything other. Holder should be fix too)
4) Publish 2 photos with better quality.

BTW.
Rhino,

What lens do you use ? ( for such photos I prefer 100 mm Macro)
What is photo distance?

On target with the lens, however Canon came out with a fairly new one which I use on our 20d. On the 10d we use what you say.

Photo distance is roughly between a half an arm to a full arms length.

 

[Rhino]

Date: 3/20/2006 8:05:13 AM
Author: Garry H (Cut Nut)

Date: 3/20/2006 2:30:47 AM
Author: Rhino

Date: 3/20/2006 12:26:02 AM
Author: Garry H (Cut Nut)

Have you just got back from a sales training conference Rhino?

LOL! NO!

Date: 3/20/2006 12:26:02 AM
Author: Garry H (Cut Nut)

I am not saying that the LED desk lights being sold to lots of retailers and used in DD are good - I am saying they should be destroyed on sight.

I have never agreed with anyone who says high colored temp fluoro''s have any use anywhere in the jewellery industry - for any purpose from red reflectors to color grading and especially for cut grading.

But mostly I disagree with using any light that is closer than 2 meters from a diamond for visual cut grading.

Question 1: What lighting environment do you suggest a consumer view fire in when visiting their local jewelry store? an area with 2 to 5 halogens in the ceiling at least 2 meters away
Question 2: What lighting environment do you suggest a consumer view brightness in when visiting their local jewelry store? in my store I take people to the window and have them hold the stone up so the light comes from behind them, and under a section with fluoro''s (in the ceiling) - and also under the desk well out of any direct light source - but not under a close up desk light.

Here''s another question to ponder.

If bright lighting with white backgrounds make steep deeps look good ... reverse the roles for a sec mate. What would be an equally worse mistake? light only from very low angles makes a steep deep very firey around the outside edges

What I''m getting at here is this. Think of common real world everyday engagement ring conditions. Would you say most of the consumers buying engagement rings are having their diamonds mounted in prongs or bezels?
http://www.preciousmetals.com.au/product/catalogue.asp you will find most of the styles that sell outside USA are about 1/2 the height, with far less chance of back light aiding the diamond. I suspect that around 50% of GIA graded diamonds are sold outside USA.
If prongs, now think about this ... is the pavilion covered with no light being allowed from behind?

Would you say the background is bright white (such as the white paper under a desk lamp in most diamantaires offices), inky black (like the background you use to compare the cz''s) or perhaps a more neautral color (such as metal or skin underneath the diamond)?

There is however a good time to use a black background to make a judgement however if you do want to reflect real world conditions. What type of setting completely encases the pavilion and prevents any light or color from being transmitted through the top? every pendant and stud earring, and most rings because most of the light from the floor is insufficient to light up the stone - where as the Diamond Dock tray gets direct light FROM the leakage, which then makes the underneath of the pavilion in very leaky stones brighter than they would appear in a real world setting. You Rhino have often explained to people how a set diamond with ''a ring of death'' will have an ugly dark zone.
Peace,

I am amazed you have read my article and still try to defend the Diamond Dock Rhino?

Surely you have tested these things for your self by now?
Take some clients repairs with steep deep stones - and look at them dirty - as they are at book in time - and then clean them and look again - you will see that any stone with a ring of death in the real world will look shocking in that dark zone. If it is in a ring - be sure to look at it or photograph it on a finger in a ''normal'' situation.

Hi Garry,

Will respond in more detail later. Actually after reading your article and your response here further convinces me of the validitiy of the dd. There are some problems with the logic I see being presented as a case against it compared to my real world comparisons which I am making.

Before I proceed to give a detailed answer however, I would still like to know the proportions of the cz you use. A Helium or perhaps even a Sarin 3d file will suffice.

 

[Rhino]

Date: 3/20/2006 9:02:47 AM
Author: Shay37

Date: 3/20/2006 3:56:03 AM
Author: Rhino
This picture was also taken outside in natural daylight. After talking with Pete he mentioned that the pavilions should be covered since the PGS software didn''t account for light entering through the pavilion. Based on my experience with backgrounds and diamond observation I find neautral colors work best except if your mounting a diamond in a bezel mounting ... then a black background would be more appropriate.

strm, dhog, shay... can anyone identify which is which? 2 varying views of the stone yet there are commonalities in each shot. Pavilion covered or not.

Just going to take a shot in the dark here. I hope I guess right, but after studying the photo, I''m going to say painted on the left.

shay

Shay ... your eyes deceive you not. It is your unbiased opinion that counts most to me dear and thank you for answering.

 

[Serg]

re:It is my conviction that if I followed these instructions I would not be true to representing the actual apperance I am seeing Sergey. I realize a still shot may be a little more dramatic since the observer can stare while there is no movement but these optical characteristics are visible none-the-less. If I set up the camera without my body behind it, then the picture would not account for proper head and body obstruction which every single viewer will see if they were to look at the diamonds live and in person.

Rhino,

What is distance between your right eye and right boundary your head( in horizontal line)?

What is distance between lens axis and right boundary construction from photo camera, your head, your body and your arms for same horizontal line?

Human is not Cyclop, do not forget it in next time when you will do photo for explanation Cut grading

 

[michaelgem]

Sergey says:

Michael, Please publish two simple answers
1) What is GIA cut grade for Brain or Paul diamonds?
2) What is AGS cut grade for Brain or Paul diamonds?
It will stop commonalities game.
Sergey,

You are more subtle in expressing your annoyance with me than some others are, but I get it.

With all the emphasis upon the differences between GIA and AGS cut grading, I am attempting to restore a sense of proportion. The commonalities in their grading systems, in my opinion, are greater than the differences.

For instance, the answers to your questions point more to the commonalities than they do to the differences.

Paul Slegers and Brian Gavin''s normally indexed super-ideal cut diamonds receive the top grade in both AGS'' and GIA''s grading systems.

Neither organization will validate the perfection in craftsmanship exhibited by the super optical symmetry of Paul and Brian''s diamonds compared to diamonds without hearts and arrows optical symmetry.

These are commonalities.

As to painting, here is another commonality. Both organizations recommend against painting.

On the other side of the coin, this painting issue is a difference in how the two organization grade. It is difficult to understand why GIA down grades painted diamonds by as much as two grades. I also understand from John and Brian that they regularly get AGS0 Ideal with their painted diamonds.

In this instance of comparison, the differences in actual grading of painted diamonds by GIA and AGS does appear to outweigh the common belief of both orgaiizations that painting is inferior to normal indexing.

I am not currently in agreement with AGS or GIA on either the issue of optical symmetry or the issue of painting. As I said: I find optically symmetric, super-ideals with both painted and regularly indexed top halves superior in beauty to the average AGS0 or GIA Excellent. I also have the science to support that finding.

Michael Cowing

www.acagemlab.com

 

[dhog]

Date: 3/20/2006 10:34:46 AM
Author: michaelgem


Fact: No one has bothered answered my orginal questions on the first page of this thread:


couple questions:

1> diamonds are often viewed at angles like that on the hand. How is that different?


It is not too different. Whether viewers have the diamond in a tray or in a ring on their finger, they will judge its beauty by angling it face-up, toward their line-of-sight, and tilt it around from there. Individuals, depending upon their eyesight, will judge at a distance within arms length up to a close-focusing distance of about 7 to 10 inches.



2> the human head is always moving so wouldnt they pick up the other beams graphed there?


Yes


unsupported humans just dont keep their head in one position.

Also odds are that they would move for max brightness when looking at it.

From my recall of observing people looking at diamonds most would move to find the brightest look.


This is an insightfull and important observation. People do move the diamonds around to find the brightest look. That position will be when the main lighting is close, but not too close to the observer''s line of sight and his head. Under this viewing circumstance, the best cut diamonds will be preferred in brilliance (both brightness and contrast), fire and scintillation.

so in your expert opinoin??

if I was to purchase 5 new stones
using dd to evaluate the stones that I purchase and installed
in the channel band in the photo below

would the stones look gold in the middle or white, since their is no way to light up the back. these stone would all be the same as we are talking about here.

 

[JohnQuixote]

Date: 3/20/2006 9:20:20 AM
Author: michaelgem

I heart super-ideals with painted or normally indexed top halves

Many appear to be reading in to my posts on the commonalities between AGS and GIA that I have a problem with painting.

I do not, and nothing could be further from the truth. In fact I have expressed my confusion to both organizations as to why they both recommend against painting.

Like John and Brian, who sell optically symmetric, super-ideals with both painted and regularly indexed top halves, I find these diamonds superior in beauty to the average AGS0 or GIA Excellent.

I tell my clients that while AGS sets their “bar for beauty” higher than does GIA, my diamonds “answer to a higher authority” . I sell super-ideal cuts with high optical symmetry and proportions that yield the best in the attributes of diamond beauty, brilliance (both brightness and contrast), fire and scintillation.

From what I have seen, the painted diamonds offered by companies like Brian’s and the normally indexed, optically-symmetric super-ideals like those cut by Paul Slegers both satisfy my super-ideal cut criteria.

Michael Cowing

www.acagemlab.com

Michael, if you start selling I

super-ideal bumper stickers sign me up for a baker's dozen (cutter's dozen?) I don't even mind if they're painted, as long as the painter is an artist and it was not done at the expense of beauty.

I love the "higher authority" comparison. That is where the wheat and the chaff need to be separated in this thread:

Discussion of vast steep/deep allowed = chaff (I think we all understand that).
Discussion of painting/digging as it relates to common make is also chaff.
Discussion of painting done with 'higher authority' goods should not be lumped in with goods where painting was necessary to cover a mistake, etc.

 

[Serg]

re:On the other side of the coin, this painting issue is a difference in how the two organization grade. It is difficult to understand why GIA down grades painted diamonds by as much as two grades. I also understand from John and Brian that they regularly get AGS0 Ideal with their painted diamonds.


Michael,

In your comparative system.
GIA Excelent correspond AGS 0 + AGS1
GIA Very Good correspond AGS2+AGS3
GIA Good correspond AGS4+AGS5

even Difference between AGS0 and AGS2 is not MINOR for Market.
Difference between AGS0 and AGS4-5 is huge for market.

re:It is difficult to understand why GIA down grades painted diamonds by as much as two grades

Michael, It is clear for me.
If you will change your goals it will be clear for you too. Just try be objective

 

[strmrdr]

Im wondering if the biggest difference in the labs when it comes to painted girdles is the basic method of cut grading they are using.

AGS is actualy running the full data scans and if they meet the brightness and contrast criteria in the computer program they pass even with painted girdles.

GIA in whatever way is either looking at them or from the scans checking a box that says painted and they get downgraded without other considerations.

Doing it that way good pointing and digging wouldnt get downgraded by AGS but the bad kind would.
Doing it that way they would get downgraded at GIA no matter the performance.
That seems to be what is happening and would be a direct result of a proportion based system(gia) vs a performance based system(ags).

 

[JohnQuixote]

Rhino I''m trying to follow what you posted photo-wise and gemfile-wise.

Please confirm: br118kvs2painted and br118kvvs1gem (you posted them on page 5 of the prior thread) are the files for these 2 diamonds: